Donald Savage
Headquarters, Washington, D.C.
September 8, 1994
(Phone: 202/358-1547)
Jim Doyle
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-5011)
RELEASE: 94-149
NASA SELECTS MARS PATHFINDER LANDING SITE
NASA has selected an ancient flood plain on Mars as the
landing site for the 1997 mission of Mars Pathfinder, one of the first
in a new generation of small, low cost spacecraft.
Eons ago, when water flowed on Mars, great floods inundated
the landing site, located on a rocky plain in an area known today as
Ares Vallis. The site is 527 miles (850 kilometers) southeast of the
location of Viking Lander 1, which in 1976 became the first spacecraft
to land on Mars. Pathfinder will be the first spacecraft to land on
Mars since the twin Viking landers arrived almost 20 years ago.
The spacecraft, scheduled to arrive at Mars on July 4, 1997,
will parachute down to Ares Vallis at the mouth of an ancient outflow
channel chosen for the variety of rock and soil samples it may
present.
The purpose of the new Pathfinder mission is to demonstrate
an inexpensive system for cruise, entry, descent and landing on Mars,
said Project Manager Anthony Spear and Project Scientist Dr. Matthew
Golombek of NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif.
The lander, carrying a microrover, will aerobrake in the
upper Martian atmosphere using an aeroshell and a parachute. Just
before impact, airbags will inflate to cushion the landing. The
microrover will then roll out to examine the rocks and soil nearby.
Both lander and rover will carry scientific instruments and
cameras. The lander will make atmospheric and meteorological
observations during descent and function as a weather station on the
surface, as well as a radio relay station for the rover.
The constraints on the landing site location have to do with
engineering considerations, Spear said. Since the spacecraft are
solar-powered, the best site is one with maximum sunshine and in July
1997, the Sun will be directly over the 15 degrees north latitude
region of the planet.
The elevation must be as low as possible, Spear added, so the
descent parachute has sufficient time to open and slow the lander to
the correct terminal velocity. The landing will be within a 60- by
120-mile (100- by 200-kilometer) ellipse around the targeted site due
to uncertainties in navigation and atmospheric entry.
Ares Vallis, which meets the engineering constraints, was
chosen after a workshop earlier this year that involved the invited
participation of the entire Mars scientific community. More than 60
scientists from the United States and Europe attended.
The Ares Vallis site also is a "grab bag" location, according
to Golombek, located at the mouth of a large outflow channel in which
a wide variety of rocks are potentially within the reach of the rover.
Even though the exact origins of the samples would not be known, he
said, the chance of sampling a variety of rocks in a small area could
reveal a great deal about Mars.
The rocks would have been washed down from highlands at a
time when floods moved over the surface of Mars. Several potential
sites were listed where ancient flood channels emptied into Chryse
Planitia, having cut through crustal units and ridged plains where the
water would have picked up material and deposited it on the plain.
Other sites that were considered included Oxia Palus, a dark
highlands region that contains highland crust and dark wind-blown
deposits; Maja Valles Fan, a delta fan which drained an ancient
outflow channel; and the Maja Highlands, just south of Maja Valles.
All of the sites were studied using Viking orbiter data.
Both the Pathfinder lander and rover have stereo imaging
systems. The rover carries an alpha proton X-ray spectrometer that
will enable examination of the composition of the rocks. The imaging
system will reveal the mineralogy of surface materials as well as the
geologic processes and surface-atmosphere interactions that created
and modified the surface. The instrument package also will enable
scientists to determine dust particle size and water vapor abundance
in the atmosphere.
JPL manages the Mars Pathfinder mission for NASA's Office of
Space Science, Washington, D.C.
-end-
NOTE TO EDITORS: A Viking photograph of the landing site is available
to news media representatives by faxing your request on letterhead to
the Headquarters Broadcast and Imaging Branch, 202/358-4333. Photo
numbers are: color: 93-HC-405, 93-HC-406, 93-HC-407; and B&W:
93-H-449, 93-H-450, 93-H-451, 94-H-239. In addition, a 9-minute video
animation is available by fax request at the same number.
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